This invention relates to associative digital data memory systems, and more specifically to an associative memory system in large-scale-integrated semiconductor technology, comprising word-organized and bitwise maskable fully associative memory devices which can be arranged in a memory array with a plurality of rows and columns and a control unit for determining and evaluating match information and for handling data transfer via the system interface. This memory system is usable in digital computer systems of all types where it may be employed as a component part of the main memory, as supplement of the main memory for specific duties, as peripheral memory, e.g. for data base problems, as auxiliary means for certain control and management tasks within the computer as well as a component of an associative processor.
Associative memory systems are known for years in numerous varieties. As far as they are built in semiconductor technology, they make use of devices having only a small storage capacity, e.g. Type 3104 of Intel Corp. (see Data Sheet of May 1971) or Type 93402 of Fairchild Semiconductor (see TTL Data Book of June 1972), which respectively contain only 16 bits. An appreciable increase of capacity is not opposed by the insufficient bit density on the silicon chips any more in view of rapid advances in technological developments, but by the high package cost for the chips. Since each memory word requires an external connection for the match indication, the number of package pins increases linearly with the number of words on the chip. Thereby, not only does the production cost become uneconomical very rapidly, but also the reliability of such components decreases significantly.
German Offenlegungschrift 2,525,287 discloses an associative memory which is intended to reduce the number of external connections. It has the disadvantage that of the entire memory capacity only a partial range is associatively accessible at any one time. Within this partial range, for each word a separate match line with an external pin is required.